 ops: : (看看Astrophysics的老板如何说)http://voltaire.csun.edu/roland/index.html
从左到右7个目镜的比较
以下是Roland的原话:"The left most eyepiece is my standard, a 25mm Zeiss Abbe Ortho with a proper multi-coating applied. Next to that is a high quality multi-element Japanese ocular. Both these eyepieces represent the state of the art in high transmission, low scatter optics. Transmission over the visible range is on the order of 97%. The third eyepiece is a popular wide field design. The coating is not too bad, but there is definitely more reflection especially in the blue end of the spectrum. This eyepiece is also the one that is compared in transmission in photo # 2.
The 4th eyepiece is another similar wide field. The 5th is an
inexpensive 12.5mm Ortho. Just because it's an Ortho does not mean it has good coatings or good transmission characteristics. #6 and #7 are real stinkers(臭名昭著), even more so because these are some of the most expensive (and popular) eyepieces on the market today. They have many elements, and a very wide field, but their coatings are really not optimized. Another problem that can be readily seen is that there are heavy reflections from internal spacer rings that appear to be black anodized, but not blackened properly. At real low angles, a black anodized surface can be very reflective, resulting in the shiny ring seen in the eye end.
Although all the eyepieces in this picture are "multicoated", they are not optimized. The different elements in a typical wide angle ocular are made from different index glass. For each index there exists an optimum coating design, one that will achieve the lowest reflectivity for that element. For optimum efficiency, each element must be coated with a different coating design according to its refractive index. What is often done is to coat all elements with the
same formula. This results in some wavelengths getting attenuated
more than others, usually in the blue end of the spectrum. These eyepieces will show a distinct yellowing of the image, as well as an
overall lower transmission efficiency.
从左到右:25毫米蔡司阿贝, 日本目镜(象Pentax或尼康的), 一种流行的广角目镜, 广角目镜, 12.5毫米Or目镜(应该是UO的单层膜Or), 市面上流行的最贵的两类目镜(虽然没有点名批评, 感觉在暗指当今时髦的多片结构名牌目镜.) |
显身卡
看来这里得分最高的还是蔡司的Or目镜, 仔细看了一下威信LVW和Nagler T4的对比, 它的各项分值跟我的实际使用效果非常吻合.
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